Heretofore, others have suggested friction disc planetary transmissions. One such transmission is shown in U.S. Pat. No. 1,423,067, wherein the driving disc is shifted in the direction of the axis of the driven wheels so as to provide infinitely variable forward and reverse output speeds from the bevel gear planetary unit whose side gears carry driven friction wheels. A coil spring surrounding the input shaft to which the driving disc is connected provides the required pressure for the driving disc against the driven friction wheels. Free wheeling of the transmission is achieved by a foot pedal operated throwout connected to move the input shaft and the driving disc axially away from the driven friction wheels.
Another pertinent prior art patent is U.S. Pat. No. 1,576,399 wherein a planetary unit housing provides the support for the friction wheel planetary transmission and wherein a friction disc is mounted for shifting movement in the direction of the axis of an input shaft, the latter being connected to one side gear and to one of the friction wheels. The friction disc is mounted on a shaft which is pivotally supported on the planetary housing for swinging movement about an axis perpendicular to and intersecting the axis of the driving disc shaft. The input to one of the friction wheels also inputs at the same speed to the planetary unit through a side gear, and the driving disc which is driven by the first mentioned friction wheel drives a second friction wheel which is connected to the other side gear. The output shaft of the transmission is connected to the spider carrying the planet bevel gears. Means are provided to provide a direct drive through the planetary unit by disengaging the driving disc and braking the friction wheel which is not associated with the input shaft.